1. ANIMAL KINGDOM

2. Main Characteristics Multicellular eukaryotes Heterotrophs Specialized cells; most have tissues Response to stimuli by nervous and muscular tissue Most capable of locomotion; few sessile Most diploid and reproduce sexually

3. Animals live in diverse habitats Marine –Origin of animal life –Provides buouyancy –Body fluids isotonic to environment –Plankton, nekton, sessile Freshwater –Requires osmoregulation –More challenging than marine: food, oxygen, sunlight, temperature

4. Terrestrial – avoid dessication: –Body covering to reduce evaporation –Respiratory organs deep in body cavity –Reproduction Return to water Internal fertilization –Eggs with coverings –Means of thermoregulation

5. Evolution of Animals All animals have a common protist ancestor: choanoflagellate –Cells of colony became specialized –Division of labor resulted in single organism Diversity results from changes in development that lead to changes in body plans –Hox genes control early development

6. Animals can be Classified According to Body Symmetry Asymmetry –no regular arrangement Radial symmetry –similar structures arranged around central axis Bilateral symmetry –can only be divided through one plane (midline) – get roughly = left and right halves

8. Cephalization Found in bilaterally symmetrical organisms Concentration of sensory structures in a head –Nerve cells concentrate in head  brain –Nerve cord extends toward rear Bilateral symmetry and cephalization are adaptations to locomotion

9. Embryonic Development Zygote formed through fertilization Undergoes cleavage – series of mitotic division Develops into blastula – hollow ball of cells Undergoes gastrulation – formation of specific layers of tissue called germ layers

11. 2 Types of Cleavage Patterns Radial –Parallel or right angles to axis –Fate of cell comes later –Indeterminate Spiral –Diagonal to axis –Fate of cell fixed early –Determinate

12. Germ Layers Form in all animals except sponges 3 layers: –Ectoderm – outer layer –Endoderm – inner layer –Mesoderm – middle layer DIPLOBLASTIC TRIPLOBLASTIC

13. Overview of Animal types Sponges – loose arrangement of different types of cells; do not have tissues Diploblastic –Cnidarians and Ctenophores –Only have 2 germ layers – endo and ectoderm Triploblastic –Have 3 rd germ layer - mesoderm

14. Body Cavity Triploblastic organisms further grouped base on presence and type of coelom – fluid- filled cavity between digestive tract and body wall

15. Body Cavity Classification Acoelomates –Solid body; no cavity –Flatworms and ribbon worms

16. Pseudocoelomates –Have a body cavity but it is not completely lined with mesoderm –Nematodes and rotifers Coelomates –Tube-within-a-tube body plan –Coelom completely lined with mesoderm Comparison

17. 2 main groups of bilateral animals: During gastrulation, group of cells move in forming sac … embryonic gut If blastopore becomes mouth – organism is a protostome If blastopores becomes anus - deuterostome

18. Protostomes vs. Deuterostomes PROTOSTOMES Flatworms, annelids, arthropods, mollusks SPIRAL CLEAVAGE Developmental fate of embryo fixed early = determinate DEUTEROSTOMES Echinoderms and chordates RADIAL CLEAVAGE Fate of embryo occurs later = indeterminate

19. Fig. 29-7, p. 627